85-87-89-91-93

Had an issue with the truck which the tech asked which grade fuel I used. I told him 93 he ask why and then gave me this speech on how I was wasting my money because all Cadillac’s were designed to run on 87. SO, I’m asking you guys what fuel you all are running and is this true. The manual didn’t really say. I know at sometimes some technicians are known to “blow smoke” if you will…